English abstract

There is an increase in infections caused by extended-spectrum beta-lactamases (ESBL) producing strains of Escherichia coli and Klebsiella pneumoniae, especially in intensive care units (ICUs). The aim of this study was to identify local risk factors for ESBL infection, with emphasis on defining the position of antibiotics. This study was conducted in 3 ICUs at 3 levels: 2) case-control study; 1) ecological study, and 3) isolate genotipization. Ecological study demonstrated that the use of fluroquinolones and 3rd generation cephalosporins was significantly associated with the increase in frequency of ESBL strains isolation with a delay of 2 months. The use of carbapenems, piperacillin/tazobactam, cephalosporins, aminoglicosides, glycopeptides and clindamycin was also significantly associated with the frequency of ESBL KP/EC isolates, without delay. Risk factors for ESBL infection identified in the case-control study were: duration of ICU stay, previous antimicrobial therapy, number of prescribed antibiotics, previous use of macrolides and fluoroquinolones. Mortality and inadequate antimicrobial therapy were more frequent in the ESBL group. Isolate genotipization revealed that both selection pressure and horizontal transfer are important factors for ESBL infection. This study confirms that antibiotic consumption is the main risk factor for ESBL infection. Rational use of antibiotics, especially fluoroquinolones, is needed in the control of ESBL infections in ICUs, as well as strict adherence to infection control measures.